Process for the fabrication of complex contoured bodies

ABSTRACT

A process for fabrication of preforms for complex contoured bodies is provided. In this process a pattern is prepared from the complex contoured body by first securing a covering to the surface of the body and then describing a continuous path on this covering so that a pattern can be recovered by cutting the covering along the continuous path. The pattern recovered has an interior edge, an exterior edge, a forward-end and an aft-end. The continuous path is described so that the width of the pattern is a constant. Filaments can then be laid by any suitable method in side-by-side relationship lengthwise of the pattern. The filaments covering the interior and exterior edges of the pattern are substantially parallel with these edges. The filaments are bound together with a resin providing a self-supporting preform for a complex contoured body.

United States Patent [191 Witzel, III

[54] PROCESS FOR THE FABRICATION OF COMPLEX CONTOURED BODIES JohnWitzel, III, Cumberland, Md.

[73] Assignee: Hercules Incorporated, Wilmington,

Del..

[22] Filed: Dec. 10, 1969 [21] Appl. N0.: 883,729

[75] lnventor:

[52] U.S. Cl. ..156/l69, 156/64, 156/212, 156/296 [51] Int. Cl. ..B65h81/02 [58] Field of Search ..156/64, 169, 172, 173, 174, 156/180, 212,245, 296, 313

[ 1 Jan. 16,1973

Primary ExaminerBenjamin A. Borchelt Assistant Examiner-H. J. TudorAttorney-Michael B. Keehan ABSTRACT A process for fabrication ofpreforms for complex contoured bodies is provided. In this process apattern is prepared from the complex contoured body by first securing acovering to the surface of the body and then describing a continuouspath on this covering so that a pattern can be recovered by cutting thecovering along the continuous path. The pattern recovered has aninterior edge, an exterior edge, a forward-end and an aft-end. Thecontinuous path is described so that the width of the pattern is aconstant. Filaments can then be laid by any suitable method inside-by-side relationship lengthwise of the pattern. The filamentscovering the interior and exterior edges of the pattern aresubstantially parallel with these edges. The filaments are boundtogether with a resin providing a selfsupporting preform for a complexcontoured body.

16 Claims, 9 Drawing Figures PATENTEDJMI 16 ms 3.711.350

SHEET 1 UF 2 FIG 2 FIG. 3

L3 L2 l N 3 2 DI JOHN ZE Y Eh ATTORNEY PATENTED JAN 16 I973 3,71 1. 350

SHEET 2 OF 2 FIGS JOHN WITZEL HI INVENTOR ATTORNEY PROCESS FOR THEFABRICATION OF COMPLEX CONTOURED BODIES This invention relates to aprocess for the fabrication of prefonns for complex contoured bodiesprepared from a fibrous material and a resin binder. More particularly,this invention relates to a process for preforming to an exact patternhigh modulus composites comprising high tensile strength fibers and aresin binder.

In the aerospace industry high modulus composite materials are beingemployed in the fabrication of complex structures because of theadvantages offered of low weight, stiffness and high strength. In thepast many components of high modulus composite materials have beenprepared by filament winding. Conventional filament winding techniques,are particularly satisfactory for manufacture of components in which thebasic underlying structure is a body of revolution. When filamentwinding a preform for a non-cylindrical body of revolution it isnecessary that the winding angle by continuously changed along the axisof the body of revolution in accordance with the surface characteristicsof the non-cylindrical body of revolution in order to preventoverlapping and/or gapping of the filaments. By changing the windingangle in a mathematically determined fashion, bodies of revolution canbe fabricated with standard filament winding equipment. Conventionalwinding equipment and methods are not suitable, however, for fabricatinga three-dimensional body having a smooth exterior surface but having noaxis of symmetry. Three-dimensional bodies of this type are referred toherein as complex contoured bodies. Complex contoured bodies includesuch items as helicopter blade root sections, wing edges and the like.High modulus composite materials such as boron, glass, or carbonfilaments or tapes must be hand fitted to the complex contours of suchcomponents in order to obtain the maximum stress from the material.

Complex contoured bodies have a continuously changing cross-section.Hand fitting has been required in order to obtain adequate conformity ofthe composite materials to the contoured surface. The reason for thenon-conformity of the tape or broad goods is analyzed as follows. Theperipheral distance (d) about the body measured at any linecircumscribing the surface of said body and lying in a planeperpendicular to the longitudinal axis of said body, it continuallychanging. Thus, if the path length of two adjacent filaments wound aboutthe peripheral surface of a complex contoured body were measured, therewould be a slight difference in length of the filaments due to thecontours of the component. This difierence in length between any twoadjacent filaments will change depending upon the surface geometry ofthe contoured surface. Unlike a body of revolution, this change incontour is not readily definable mathematically. In the case of tapes,the difference in lengths between two adjacent tapes laid on a contouredsurface is often great enough that the second tape will not conform tothe surface of the contoured body without either buckling or causing agap between the tapes of filaments.

Several alternative methods of laying filaments or tapes on a complexcontoured body are possible. One approach to this problem would be toprepare custom made tapes in which the length of each filament withinthe tape or broad goods is adjusted so that the resulting tape or broadgoods would conform to the surface of the complex contoured body.Another method would be to continually reduce the width of the tape orthe filaments to minimize the difference in length between any twofilaments being wound about the complex contoured body. As heretoforementioned there is no known winding equipment which can be employedsatisfactorily for winding filaments on such a body. Similarly, custommade broad tapes are required for this application are not commerciallyavailable, and would be extraordinarily expensive to produce.

Accordingly, it is an object of this invention to provide a method forpreparing a preform from fibrous materials and a resin binder which willconform to the surface of a complex contoured body.

It is another object of this invention to provide a method formanufacture of complex contoured bodies from high modulus compositematerials employing conventionally prepared filaments or tapes.

It is another object of this invention to provide a method for preparinga preform from high modulus composite materials which will conform tothe surface of a complex contoured body.

It is another object of this invention to provide a simplified methodfor manufacture of complex contoured bodies from high modulus compositematerials employing conventional filament winding equipment.

It is another object of this invention to provide a simplified methodfor manufacture of small numbers or large quantities of complexcontoured bodies from high modulus composite materials.

Other objects of this invention will, in part, be obvious and will, inpart, appear hereinafter. For a complete understanding of the nature ndobjects of this invention, reference is made to the following detaileddescription.

In accordance with this invention a method has been found for preparinga preform from filaments and a resin binder which will conform to thesurface of a complex contoured body. The preform of this invention isprepared by laying filaments on a pattern or mandrel prepared from apattern made from the complex contoured body, and binding the filamentswith a resin to provide a self-supporting preform. The first step inpreparing the pattern for the preform is to secure a covering of apliable material to the surface of the complex contoured body. Thepliable material must conform substantially to the surface of thecomplex contoured body. Next, a continuous path is described about thesurface of the covering. The pliable covering is out along thiscontinuous path to provide the pattern on which the preform isultimately prepared. The continuous path described is therefore criticalto this invention and must be described so that the pattern recovered bycutting along the continuous path will have two edges, referred toherein as an interior edge and an exterior edge, and two ends. The widthof the pattern measured between the interior edge and exterior edgesthereof along a line passing through said pattern and perpendicular toany tangent to either edge of the pattern is a constant. Discontinuityin the pattern width can occur only at the ends of the pattern.

The pattern thus defined is removed from the complex contoured body bycutting the pattern along the continuous path described. The patternthus removed has gentle contours along the length of the pattern.Filaments or tapes are laid on the surface of the pattern in contactwith resin in side-by-side relationship lengthwise of said pattern andsubstantially parallel to said continuous path at the exterior andinterior edges of the pattern. Sufficient filaments are laid on thepattern until the pattern is completely covered with filaments. The termcontinuous pat is defined herein to mean the path about a complexcontoured body which serves as a reference line on which and from whichfilaments can be laid in side-by-side relationship in preparing afilament based composite without gaps or laps occurring between thefilaments in the composite.

In the preferred practice of this invention, a mandrel is first preparedhaving the same shape as the complex contoured body. This mandrel iscovered with a pliable covering such as glass scrim or cloth. The scrimis coated with a resin which will cause the scrim to conform to thesurface of the complex body and to bond it together as an integralcovering. A continuous path is then described about the resin coatedcovering as previously described. The scrim is cut along this continuouspath providing a pattern. A second pattern is prepared from a rigidmaterial such as sheet aluminum conforming to the surface of the clothpattern. The ends of the new pattern are then joined to form a newsmooth surface about a longitudinal axis. The pattern ends are joined toform a surface which is continuous at the intersection of the ends. Itis not necessary that the ends of the pattern intersect along theirentire length and for most complex contoured bodies they will not sointersect. This new surface is reinforced by any suitable means and isdisposed about a spindle coinciding with the longitudinal axis to form anew mandrel. Employing the new mandrel, filaments or tapes are wounddirectly onto the mandrel employing conventional equipment. Thefilaments or tapes are resin coated and are partially cured or B-stagedto form a continuous filament wound preform. B-staged is the termcommonly used to describe a semi-cured or partially cured state whereinthe resin goes from a fluid state to an elastic state which provides asufficiently strong bond but is nevertheless still flexible. Theresulting preform is cut from the new mandrel along the intersection ofthe joined ends of the mandrel. This preform can then be wrapped aboutthe original mold or mandrel, said wrapping being performed so that thelongitudinal axis about which the preform is positioned is the originallongitudinal axis of the mandrel from which the pattern was prepared.This transformation of axes is referred to as topological transform.This transform is accomplished by joining the interior and exterioredges of preform about the complex contoured body to reconstitute theoriginal continuous path about said complex body. The preform is thenfinally cured about the mold to bind the filaments into a strongfilament wound body in which the filaments are continuous from one endto the other.

In the process as heretofore described it is necessary to described acontinuous path about the surface of the mandrel so that the pattern cutfrom the mandrel has a substantially constant width between the interiorand exterior edges of said pattern as measured by a line perpendicularto any tangent to either edge of said pattern, said line passing throughsaid pattern. Theoretically, this continuous path can be determinedmathematically from the equation describing the surface of the complexbody. Except in very simple cases, however, mathematical calculation ofthe continuous path is quite difficult. An approximation to the desiredcontinuous path has been found which will permit describing of a pathabout the complex body and which will permit cutting of a pattern fromsaid body from which a preform can be made which will conform to thesurface of the body with substantially no gaps and no laps in thewinding of the preform.

The approximation for laying the continuous path on said complexcontoured body is described in relation to the angle of winding 6,measured with respect to the longitudinal axis of the body at anyperipheral line I, defined at the intersection of a plane perpendicularto the longitudinal axis of the body with the surface of the body. Anyperipheral line L about the complex contoured body has a total length d,Assuming a filament or tape having a thickness 1, the number offilaments F required to cover line L when the filaments cross line L, atan angle 0 is defined by the expression F r/fr u) where f, is thedistance covered along line L by one filament f of thickness (t) at theangle 0 In order for there to be no gaps or laps in a winding, the ratioof peripheral distance d, to the distance covered by the filament fshould be a constant. From the foregoing relationship the angle of wind9, at any peripheral line I. can be determined by the expression:

608 (0/ (2) where F and t are constants as heretofore described and thesubscript (n) refers to any given peripheral line about the surface ofthe complex contoured body.

When employing the foregoing method as an approximation of the truecontinuous path about the complex contoured body, it is to be understoodthat any number of peripheral lines can be employed. The greater thenumber of peripheral lines L that are drawn, the closer will be thecontinuous path described to the true continuous path whereby the widthof the pattern recovered will be a true constant.

The following drawings will more fully illustrate this invention.Reference symbols refer to like parts wherever they occur.

FIG. I is an elevation of a complex contoured body.

FIGS. 2 and 3 illustrate cross-sections taken through the complexcontoured body of FIG. 1.

FIG. 4 is a front view of the complex contoured body of FIG. 1 which hasbeen covered with a cloth and marked with peripheral lines about thebody.

FIG. 5 is an elevation of the complex contoured body of FIG. 4illustrating a continuous path about the longitudinal axis of said body.

FIG. 6 is a top view illustrative of a pattern that could be cut fromthe complex contoured body of FIG. 5 along the continuous path describedin FIG. 5.

FIG. 7 is a diagrammatic view of a mandrel prepared from the pattern ofFIG. 6.

FIG. 8 is a cross-sectional view of the mandrel of FIG. 7.

FIG. 9 is a diagrammatic view of winding of a preform on the mandrelillustrated in FIG. 7.

In FIG. 1 a mandrel 10 is illustrated having the shape of a complexcontoured body. FIG. 2 illustrates a crosssection through the mandrel ofFIG. 1 at lines 2-2. FIG. 3 illustrates a cross-section through themandrel of FIG. 1 at lines 3-3.

In FIG. 4 the mandrel is shown covered with a cloth which has been resinimpregnated to cause adherence of the cloth to the mandrel surface. Themandrel surface is marked with peripheral lines L,, L L L each linehaving a length d d d d,,, said peripheral lines being spaced at equalincremental distances across the surface of the mandrel. Folds 14-16caused by overlapping of the cloth covering are shown illustrating thatsuch overlap can occur in winding the cloth covering about the mandrel.The interior surface of the resin impregnated cloth, however, adheres tothe surface of the mandrel tightly as if no overlapping exists.

FIG. 5 illustrates continuous path 12 drawn across the surface ofcovered mandrel 10 so that the distance (width) 18 between the interioredge 20 and exterior edge 22 of the pattern which could be cut from themandrel 10 along continuous path 12 is substantially a constant.

Continuous path 12 is drawn across mandrel 10 as follows: An initialwinding angle 0 which is the angle of the filament measured with respectto the longitudinal axis of the mandrel, is established at someconvenient point on line L From the relationship heretofore described inequation (I) the number of filaments F of thickness (t) required tocover line L having a peripheral length 11 when crossing I at an angle 0is thereby established. Holding F constant, the angles, 0 -0,, arecalculated. A continuous path 12 is then drawn starting from line L suchthat the path is a smooth curve passing through lines, L,, L l at theangles 0,, 6 -6,, corresponding to lines L,, L -L In FIG. 6 a pattern 24cut from the cloth covering on mandrel 10 along continuous path 12 isshown after the pattern has been removed from the mandrel 10. The curedresin impregnated cloth remains as a unitary or one-piece pattern aftercutting due to the bonding action of the resin. The interior edge 20,exterior edge 22, forward-end 26 and aft-end 28 of the pattern 24 areclearly identifiable.

FIG. 7 illustrates the topological transform that results from joiningthe forward-end 26 and aft-end 28 of pattern 24 about a longitudinalaxis 30 and supporting said pattern to form a mandrel. The pattern 24 isshown as it would appear stretched over a mandrel 32 prepared from arigid material and having the configuration of pattern 24 and which hasundergone topological transform as heretofore described with theexception that the mandrel is made with a continuous surface tofacilitate winding. The mandrel 32 has a spindle 33 centered onlongitudinal axis 30. The mandrel edges conform to the interior edge 20and exterior edge 22 of the pattern. The pattern ends 26 and 28 arejoined and intersect along line 34. A gap 36 is shown illustratingdiscontinuity in the pattern that can result depending on the shape ofthe ends of the complex contoured body. The mandrel 32 prepared frompattern 24 has surface protrusions 38 illustrative of the surface of themandrel 32 resulting from topological transform.

FIG. 8 is a cross-section taken through FIG. 7 at lines 8-8 furtherillustrating the mandrel 32 and surface protrusion 38. The mandrelsurface 40 is supported to the mandrel spindle 33 by support members 42.

In FIG. 9 the mandrel 32 of FIG. 7 is shown as it might appear in afilament winding operation. The mandrel is illustrated as if the pattern24 is again stretched over the surface of the mandrel as referred to inFIG. 7. The mandrel of FIG. 9 is rotated approximately 45 from itsposition in FIG. 7 so that protrusion 38 appears as part of the bottomedge of this view. Filament 44 is fed from spool 46 and is wound aroundthe surface of mandrel 33 so that the individual filaments are inside-by-side relationship and are substantially parallel with theinterior edge 20 and exterior edge 22 of the pattern 24. It is clearthat some angle between adjacent windings about the mandrel exists, yetthe filaments are defined as substantially parallel within this context.The filaments pass through a resin spray 48 prior to being wound aboutthe mandrel 33. The resulting winding is cut from the mandrel along thepattern intersection 34 and along the non-intersecting edges 26 and 28.Filament 44 is stored on spool 46 which in turn is mounted on a spoolpin 50 upstanding from a platform 52 of a filament feed mechanism. Thespool 46 is loose on the spool pin 50 so that it is free to turn as thefilament 44 is pulled from it. The platform 52 is mounted for slidingendwise or axially of a pair of rods 54 that are disposed parallel tothe axis of the spindle 33 of mandrel 32, and which define thefilament-laying axis along which the filament feed mechanism is moved.The platform 52 is adapted to be driven along the rods 54 by a drivelink 56 that may be actuated by a programmed mechanism (not shown)whereby the platform 52 will traverse the mandrel 32 and filament 44 islaid onto the mandrel surface in side-by-side relationship.

The preforms of this invention are composite materials prepared fromfilaments and a resin employed in an amount sufficient to bind togetherthe filaments of each layer as well as those of various superposedlayers and to fill any interstices that may exist between any of thefilaments. The preform is generally comprised of high tensile strengthfilaments with the quantity of resin being kept to the minimum necessaryto provide a consolidated uniform preform. The resin can be applied tothe filaments by any suitable means. Thus, for example, the filamentsemployed can be preimpregnated with resin or they can be sprayed withresin during the winding operation.

All types of fibers or filaments can be employed in producing thepreforms of this. invention. Particularly suitable materials are fiberscharacterized by a high tensile strength and light weight. Illustrativefibers having these characteristics are prepared from glass, boron,carbon, asbestos, aluminum oxide (A1 0 and sapphire. These fibers orfilaments can be employed in any configuration such as single filamentshaving a circular cross-section area or as tapes consisting of a singlelayer of oriented filaments, that is, filaments in parallel side-by-siderelationship extending lengthwise of the tape.

The resins which can be employed as a binder in manufacturing thepreforms of this invention are curable thermosetting resins such asepoxy polymers and thermoplastic resins. These resins bind the filamentscomprising the preform together into a high modulus composite material.Thermosetting resins are preferred and are partially cured or B-stagedto solidify the resin and to provide a preform which is structurallyself-supporting. By the term self-supporting preform is meant that thecomposite comprised of numerous individual filaments and resin has thecharacteristics of a flexible, integral solid. The partially curedpreform can be readily handled and stored in this condition. When readyfor final use the preforms are assembled or employed as needed for aparticular application and completely cured employing heat, pressure ora combination thereof. Thermoplastic resins used to prepare the filamentwound preforms of this invention are employed in the fused state and arecooled to solidify the resin and to provide a preform which isself-supporting.

The method of making filament wound preforms heretofore described bypreparing a mandrel based on the pattern cut from the complex contouredbody and filament winding the preform as illustrated in FIG. 8 ispreferred. While this process is undoubtedly the most convenient methodfor laying of filaments on the pattern or mandrel thus prepared, it isclear that preparation of a mandrel from the pattern cut from thecomplex contoured body is not the only way to utilize the pattern. Thus,when manufacturing small numbers of preforms, it may be desirable to usehand lay-up techniques to prepare the preform. In this method, filamentsor tapes are laid from one end of the pattern to the other, saidfilaments being parallel with the interior edge and exterior edge of thepattern as herein defined. These filaments are laid in a side-by-siderelationship. Each filament or tape is therefore substantially parallelto the next adjacent filament or tape. Thus, the process of thisinvention while particularly adaptable to manufacture of large numbersof preforms for complex contoured bodies employing conventional filamentwinding methods can be readily employed for preparing single or smallnumbers of preforms. Laying of filament on the pattern prepared from thecomplex contoured body can also be accomplished employing the devicedisclosed in the pending application of K.E. Moran; Ser. No. 745,854entitled Apparatus for Making Composite Filamentary Structures, now US.Pat. No. 3,521,877.

What I claim and desire to protect by Letters Patent l. The process ofpreparing a filament wound preform for a complex contoured bodysaid'process comprising:

a. making a mandrel shaped to the contoured surface of the complexcontoured body,

b. securing a covering to the surface of the mandrel so that said coverconforms to said mandrel surface,

. describing a continuous path on the surface of said covering about theentire longitudinal axis of said mandrel to define a pattern, saidpattern having an interior edge and exterior edge that are formed bycutting along the continuous path and a forwardend and an aft-end, thewidth of the pattern measured between the interior edge and exterioredge of the pattern along a line through said pattern perpendicular toany tangent to either edge of the pattern being substantially constantexcept at the forward-end and the aft-end of the pattern,

. cutting the covering along the continuous path to make said pattern,

e. laying filaments in side-by-side relationship lengthwise of saidpattern from one edge to the other, and

f. binding the filaments with a resin to provide a selfsupportingpreform for the complex contoured body.

2. The process of claim 1 wherein the resin employed 7 for binding thefilament is a thermosetting resin, said thermosetting resin beingpartially cured to provide the self-supporting preform.

3. The process of claim 1 wherein the resin employed for binding thefilaments is a thermoplastic resin.

4. The process of claim 2 wherein the filaments are preimpregnated witha thermosetting resin prior to laying of the filaments in side-by-siderelationship on the pattern.

5. The process of preparing a filament wound preform for a complexcontoured body, said process comprising:

a. making a first mandrel shaped to the contoured surface of the complexcontoured body,

securing a covering to the surface of the first mandrel so that saidcover conforms to said surface,

. describing a continuous path on the surface of said covering about theentire longitudinal axis of said first mandrel to define a pattern, saidpattern having an interior edge and exterior edge that are formed bycutting along the continuous path and a forward-end and an aft-end, thewidth of the pattern measured between the interior edge and exterioredge of the pattern along a line through said pattern perpendicular toany tangent to either edge of the pattern being substantially constantexcept at the forward-end and the aft-end of the pattern,

d. cutting the covering along the continuous path to make said pattern,

joining the forward-end and aft-end of said pattern about a longitudinalaxis so as to form a continuous surface having ends corresponding to theinterior and exterior edges of said pattern,

. making a second mandrel having a surface corresponding to saidcontinuous surface and ends corresponding to the interior and exterioredges of said pattern,

. laying filaments in side-by-side relationship about said secondmandrel, said filaments being laid in a direction substantially parallelto the ends of said second mandrel,

h. binding the filaments with a resin to provide a selfsupportingpreform, and

i. cutting the preform from the second mandrel along lines correspondingto the forward-end and aft-end of said pattern.

6. The process of claim 5 wherein the filaments are laid in side-by-siderelationship about the second mandrel employing a filament windingapparatus.

7. The process of claim 6 in which the resin employed for binding thefilaments is a thermosetting resin.

8. The process of claim 6 in which the resin employed for binding thefilaments is a thermoplastic resin.

9. The process of claim 7 in which the covering secured to the surfaceof the first mandrel is a cloth which has been impregnated with athermosetting resin, said resin impregnated cloth being cured so thatthe resulting resin cured covering when cut from said first mandrelalong the continuous path results in a pliable and unitary pattern.

10. The process of preparing a filament wound preform for a complexcontoured body, said process comprising:

a. making a first mandrel shaped to the contoured surface of the complexcontoured body, securing a covering to the surface of the first mandrel,said cover conforming to said first mandrel surface,

c. drawing a series of continuous peripheral lines, L and L about thesurface of the covering of the first mandrel, said continuous peripherallines being defined by the intersection at the surface of the firstmandrel of a series of cross-sections through the first mandrelperpendicular to the longitudinal axis thereof,

d. measuring the length (d) of each continuous peripheral line (L),

e. establishing an angle of wind 6 at a peripheral line L having alength d,, said angle of wind (9 measured with respect to thelongitudinal axis of the first mandrel,

f. determining the number of filaments F of thickness t required tocover line L when laid at an angle 0, from the relation F= (d cos g.determining the winding angles 6 to 6,, for

peripheral lines L to L, from the relation where F is the number offilaments determined from step (f), t is the filament thickness, and d,is the length of a peripheral line,

b. laying a continuous path through peripheral lines L to L,,, saidcontinuous path crossing each peripheral line L to L at the determinedwinding angle 0, to 0,, respectively,

i. cutting the covering along the continuous path to make a patternhaving an interior edge, exterior edge, forward-end and aft-end,

j. laying filaments in side-by-side relationship lengthwise of saidpattern substantially parallel to said interior and exterior edges, and

k. binding the filaments with a resin to provide a selfsupportingpreform for a complex contoured body.

11. The process of claim 10 in which the filament wound preform isprepared from said pattern by the steps comprising:

a. joining the forward-end and aft-end of said pattern about alongitudinal axis so as to form a continuous surface having endscorresponding to the interior edge and exterior edge of said pattern,

b. making a second mandrel having a surface corresponding to saidcontinuous surface and ends corresponding to said interior and exterioredges of said pattern,

. laying filaments in side-by-side relationship about said secondmandrel, said filaments being laid in a direction substantially parallelto the ends of said second mandrel, binding the filaments with a resinto provide a selfsupporting preform, and

e. cutting the resulting preform from the second mandrel along linescorresponding to the forwardend and aft-end of said pattern.

12. The process of claim 11 in which the filaments are laid inside-by-side relationship employing a filament winding apparatus.

13. The process of claim 12 in which the filaments are preimpregnatedwith resin prior to laying of the filaments in side-by-side relationshipon the second mandrel.

14. The process of claim 13 in which the resin employed is athermosetting resin.

15. The process of claim 13 in which the resin employed is athermoplastic resin.

16. The process of claim 14 in which the covering secured to the surfaceof the first mandrel is a cloth winding which has been impregnated witha thermosetting resin, said resin impregnated cloth being cured so thatthe resulting resin cured covering when cut from said first mandrelalong the continuous path results in a pliable unitary pattern.

2. The process of claim 1 wherein the resin employed for binding thefilament is a thermosetting resin, said thermosetting resin beingpartially cured to provide the self-supporting preform.
 3. The processof claim 1 wherein the resin employed for binding the filaments is athermoplastic resin.
 4. The process of claim 2 wherein the filaments arepreimpregnated with a thermosetting resin prior to laying of thefilaments in side-by-side relationship on the pattern.
 5. The process ofpreparing a filament wound preform for a complex contoured body, saidprocess comprising: a. making a first mandrel shaped to the contouredsurface of the complex contoured body, b. securing a covering to thesurface of the first mandrel so that said cover conforms to saidsurface, c. describing a continuous path on the surface of said coveringabout the entire longitudinal axis of said first mandrel to define apattern, said pattern having an interior edge and exterior edge that areformed by cutting along the continuous path and a forward-end and anaft-end, the width of the pattern measured between the interior edge andexterior edge of the pattern along a line through said patternperpendicular to any tangent to either edge of the pattern beingsubstantially constant except at the forward-end and the aft-end of thepattern, d. cutting the covering along the continuous path to make saidpattern, e. joining the forward-end and aft-end of said pattern about alongitudinal axis so as to form a continuous surface having endscorresponding to the interior and exterior edges of said pattern, f.making a second mandrel having a surface corresponding to saidcontinuous surface and ends corresponding to the interior and exterioredges of said pattern, g. laying filaments in side-by-side relationshipabout said second mandrel, said filaments being laid in a directionsubstantially parallel to the ends of said second mandrel, h. bindingthe filaments with a resin to provide a self-supporting preform, and i.cutting the preform from the second mandrel along lines corresponding tothe forward-end and aft-end of said pattern.
 6. The process of claim 5wherein the filaments are laid in side-by-side relationship about thesecond mandrel employing a filament winding apparatus.
 7. The process ofclaim 6 in which the resin employed for binding the filaments is athermosetting resin.
 8. The process of Claim 6 in which the resinemployed for binding the filaments is a thermoplastic resin.
 9. Theprocess of claim 7 in which the covering secured to the surface of thefirst mandrel is a cloth which has been impregnated with a thermosettingresin, said resin impregnated cloth being cured so that the resultingresin cured covering when cut from said first mandrel along thecontinuous path results in a pliable and unitary pattern.
 10. Theprocess of preparing a filament wound preform for a complex contouredbody, said process comprising: a. making a first mandrel shaped to thecontoured surface of the complex contoured body, b. securing a coveringto the surface of the first mandrel, said cover conforming to said firstmandrel surface, c. drawing a series of continuous peripheral lines, L1and Ln, about the surface of the covering of the first mandrel, saidcontinuous peripheral lines being defined by the intersection at thesurface of the first mandrel of a series of cross-sections through thefirst mandrel perpendicular to the longitudinal axis thereof, d.measuring the length (d) of each continuous peripheral line (L), e.establishing an angle of wind theta 1 at a peripheral line L1 having alength d1, said angle of wind theta 1 measured with respect to thelongitudinal axis of the first mandrel, f. determining the number offilaments F of thickness t required to cover line L1 when laid at anangle theta 1 from the relation F (d1 cos theta 1/t) g. determining thewinding angles theta 2 to theta n for peripheral lines L2 to Ln from therelation cos theta n Ft/dn where F is the number of filaments determinedfrom step (f), t is the filament thickness, and dn is the length of aperipheral line, h. laying a continuous path through peripheral lines L1to Ln, said continuous path crossing each peripheral line L1 to Ln, atthe determined winding angle theta 1 to theta n respectively, i. cuttingthe covering along the continuous path to make a pattern having aninterior edge, exterior edge, forward-end and aft-end, j. layingfilaments in side-by-side relationship lengthwise of said patternsubstantially parallel to said interior and exterior edges, and k.binding the filaments with a resin to provide a self-supporting preformfor a complex contoured body.
 11. The process of claim 10 in which thefilament wound preform is prepared from said pattern by the stepscomprising: a. joining the forward-end and aft-end of said pattern abouta longitudinal axis so as to form a continuous surface having endscorresponding to the interior edge and exterior edge of said pattern, b.making a second mandrel having a surface corresponding to saidcontinuous surface and ends corresponding to said interior and exterioredges of said pattern, c. laying filaments in side-by-side relationshipabout said second mandrel, said filaments being laid in a directionsubstantially parallel to the ends of said second mandrel, d. bindingthe filaments with a resin to provide a self-supporting preform, and e.cutting the resulting preform from the second mandrel along linescorresponding to the forward-end and aft-end of said pattern.
 12. Theprocess of claim 11 in which the filaments are laid in side-by-siderelationship employing a filament winding apparatus.
 13. The process ofclaim 12 in which the filaments are preimpregnated with resin prior tolaying of the filaments in side-by-side relationship on the secondmandrel.
 14. The process of claim 13 in which the resin employed is athermosetting resin.
 15. The process of claim 13 in which the resinemployed is a thermoplastic resin.
 16. The process of claim 14 in whichthe covering secured to the surface of the first mandrel is a clothwindinG which has been impregnated with a thermosetting resin, saidresin impregnated cloth being cured so that the resulting resin curedcovering when cut from said first mandrel along the continuous pathresults in a pliable unitary pattern.